Issue 5, 2016

Guidance to improve the scientific value of zeta-potential measurements in nanoEHS

Abstract

Nanoparticle zeta-potentials are relatively easy to measure, and have consistently been proposed in guidance documents as a particle property that must be included for complete nanoparticle characterization. There is also an increasing interest in integrating data collected on nanomaterial properties and behavior measured in different systems (e.g. in vitro assays, surface water, soil) to identify the properties controlling nanomaterial fate and effects, to be able to integrate and reuse datasets beyond their original intent, and ultimately to predict behaviors of new nanomaterials based on their measured properties (i.e. read across), including zeta-potential. Several confounding factors pose difficulty in taking, integrating and interpreting this measurement consistently. Zeta-potential is a modeled quantity determined from measurements of the electrophoretic mobility in a suspension, and its value depends on the nanomaterial properties, the solution conditions, and the theoretical model applied. The ability to use zeta-potential as an explanatory variable for measured behaviors in different systems (or potentially to predict specific behaviors) therefore requires robust reporting with relevant meta-data for the measurement conditions and the model used to convert mobility measurements to zeta-potentials. However, there is currently no such standardization for reporting in the nanoEHS literature. The objective of this tutorial review is to familiarize the nanoEHS research community with the zeta-potential concept and the factors that influence its calculated value and interpretation, including the effects of adsorbed macromolecules. We also provide practical guidance on the precision of measurement, interpretation of zeta-potential as an explanatory variable for processes of interest (e.g. toxicity, environmental fate), and provide advice for addressing common challenges associated with making meaningful zeta-potential measurements using commercial instruments. Finally, we provide specific guidance on the parameters that need to be reported with zeta-potential measurements to maximize interpretability and to support scientific synthesis across data sets.

Graphical abstract: Guidance to improve the scientific value of zeta-potential measurements in nanoEHS

Article information

Article type
Tutorial Review
Submitted
12 May 2016
Accepted
23 Aug 2016
First published
30 Aug 2016

Environ. Sci.: Nano, 2016,3, 953-965

Guidance to improve the scientific value of zeta-potential measurements in nanoEHS

G. V. Lowry, R. J. Hill, S. Harper, A. F. Rawle, C. O. Hendren, F. Klaessig, U. Nobbmann, P. Sayre and J. Rumble, Environ. Sci.: Nano, 2016, 3, 953 DOI: 10.1039/C6EN00136J

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